The present invention relates to a regulating device for a multi-channel cycle-controlled heating system of a motor vehicle. This system has a heat exchanger which is divided into partial heat exchangers for heating different cabin areas and is equipped with a common inlet opening for heating medium, with a throttle valve arranged at an outlet opening of each of the partial heat exchangers.
Two-channel heating systems for individual regulation of the air outlet temperature on the driver and passenger sides in motor vehicles are generally known. Such regulation is achieved by a water/air heat exchanger which is divided into two and in which different water flows and thus different air outlet temperatures are achieved by two throttle valves which are actuatable independently of one another. The throttle valves are opened for more or less time during one fixed cycle period, depending on the heat requirement.
If both throttle valves are opened at the same time, approximately equal volumes flow through both parts of the heat exchanger. If one throttle valve closes earlier with a different heat requirement, twice the volume of water per units of time flows through the section of the heat exchanger associated with the throttle valve which is still open. This leads to increased availability of heat and thus to an increase in the air outlet temperature. This increase is compensated again with a certain delay via temperature sensors but can lead to periodic fluctuations of the air outlet temperatures if the conditions are unfavorable.
For this reason, an object of the present invention is to provide an improved regulating device so that the air outlet temperatures associated with one side do not change, or only insignificantly so, when there is a change in the air outlet temperatures associated with the other side, and that during this process periodical temperature fluctuations are avoided.
This and other objects are achieved in the present invention by providing a regulating device of a heating system having a divided heat exchanger with setpoint generator means associated with the throttle valves for setting a duration of a cycle period of opening of each throttle valve according to a position of the setpoint generator means. The setpoint generator means includes control means for controlling the position of the setpoint generator means, such that the duration of opening of one of the throttle valves causes a partial quantity of the heating medium to flow through the partial heat exchanger in dependence on the duration of opening of all the other throttle valves simultaneously opened.
In a two-channel heating system, that is to say with a heat exchanger which is divided into two, the opening time is accordingly multiplied by a factor of 1 when both throttle valves are opened. For the second valve which is still open after one valve has been closed, the residual duration of opening is multiplied by a factor which can be about 0.5 and is thus shortened in such a manner that there is no noticeable increase in air outlet temperature on this side despite the higher water flow rate, using the cycle period as a basis.
A cycle period duration of about 5 seconds is a compromise since temperature fluctuations occur during a relatively long cycle period, particularly if there is a low heat requirement, and the life of the throttle valves is reduced with a shorter cycle period. In consequence, alternating pulsing of the throttle valves in successive cycle periods without different time weighting of the durations of opening of the valves is less well suited for solving the problems since then, of necessity, a gap in opening of at least one cycle period, but in most cases more, occurs which becomes noticeable in temperature fluctuations. A further division of a heat exchanger is contemplated in which, in addition to the subdivision into driver/passenger side, for example a subdivision into front/rear is undertaken.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.